EXTINCT AMPHIBIA OF NORTH AMERICA 67 
On the basis of the “perisquamosal,” which Jaekel claims for 
Diceratosaurus punctolineatus Cope, the genus was regarded by that 
author as without a parallel among the known vertebrates. Such it 
would be if Jaekel’s interpretations are correct but the morphology 
of the present skull would tend to throw grave doubt on the inter- 
pretation of this region of the skull as given for the type species. 
Another specimen representing another species also shows no evi- 
dences of the fusion of elements to form the “perisquamosal”’ and its 
presence in the type species is doubtful. So far as I can learn there 
has never been a true case of fusion in any of the cranial elements of 
the Stegocephala unless it be between the frontals of Diplocaulus 
magnicornis Cope, and I think I can detect a median suture even here. 
It was on the basis of such fusions that Maggi has proposed to derive 
the interparietal of the primates from the epiotics of the stegocepha- 
lans. 
The posterior outline of the skull in the present specimen is not 
- well preserved and the outline as given may be slightly inaccurate. 
The indentation figured by Jaekel in the posterior border of the skull 
of the type form is not present in the species under discussion. 
MEASUREMENTS OF THE SKULL OF Diceratosaurus laevis MOoDIE 
mm 
engthotesiullalongsmedrancsutures -.40. 45 acces a7 
engthyiromiamnuzzle tontip ol More... 45... 26.4. yeas eee ee 50 
Wadthibetweenitips.ot hors sestimated (5). acces ee ee 40 
NWitcicheotsonbit.aeececir ere sen oii. dirt ete elle oto A Gite 7 
Wenigthvomorbitaeareseaee etree fo. ay Mie epee teatro tee cer Gas sie) 
Wadthrotyskullvacrossithe Orbits esas. 42h. 06 os ae 30 
Imiteronbitalewacth terctet ate aS tga: daly han. ak emer annie sen 6 
Wenpthyotsmostrilt er: eee  ey a nes  e alate acts ACs 2 
WWidthyo ton ostiill sya caer ott nica y.s. nhc eh wie aan nae aes I 
Diameter, of the; pinealsforamen) less thane <seeqc0ns- 6 nasi: I 
The specimen on which the species is based is from the Linton 
deposits of Ohio and forms a part of the collection of Dr. J. S. New- 
berry now in the American Museum. It is No. 102 of the American 
Museum Collection. 
DICERATOSAURUS ROBUSTUS sp. nov. 
(Fig. 15) 
The present species is indicated by the left portion of a cranium 
representing a large individual. The characters of the skull are so 
